Light bulb



FIG. 1 is a perspective view of a light bulb;

FIG. 2 is a side elevation view thereof;

FIG. 3 is a top view thereof; and,

FIG. 4 is a bottom view thereof.

The broken lines in the figures are included for the purpose of illustrating the environment in which the design is used and form no part of the claimed design. The side elevation view in FIG. 2 represents the front, rear, left and right side views of the design because all sides are identical. 

CLAIM The ornamental design for a light bulb, as shown and described. 